Paper Title:
Crack Growth Mechanisms from 3-D Surface Flaw with Varied Dipping Angle under Uniaxial Compression
  Abstract

A number of instability problems in rock engineering projects are caused by crack propagation. However, crack growth mechanisms from 3-dimentional flaw are not fully understood, in particular for 3-D flaw case with varied dipping angle. This study focuses on 3-D surface flaw using real rock specimens containing a flaw with varied inclination angle α from axial loading and dipping angle γ from specimen surface under uniaxial compression. Acoustic emission technique was used for tracing the initiation and growth of micro-cracks inside of specimen. It was found that crack growth process is affected by the dipping angle γ of the 3-D flaw. When dipping angle γ ≠ 90º, the thickness of rock above the flaw plane is thinner than that of below the flaw plane. As a result, compressive crack and wing crack initiated easily from the thinner flaw tips. And, the normalized stress for crack initiation σi /σc, AE events and the AE energy for crack growth decreases with the dipping angle γ. However, for γ = 90º, the thickness of rock above and below of the flaw tips is the same, it was observed that anti-wing crack (crack growth direction opposite to wing crack) initiated first at a certain place away from the flaw tips, then wing crack and compressive crack emerged at the late stage. For this case, the stress σi /σc, AE events and the AE energy for crack initiation and propagation are at a high value. Thus, for rock mass contains flaws geometry with small dipping angle, some problems of crack propagation may be induced easily during excavation.

  Info
Periodical
Key Engineering Materials (Volumes 353-358)
Edited by
Yu Zhou, Shan-Tung Tu and Xishan Xie
Pages
2353-2356
DOI
10.4028/www.scientific.net/KEM.353-358.2353
Citation
Y.S.H. Guo, R.H.C. Wong, K.T. Chau, W. S. Zhu, S. C. Li, "Crack Growth Mechanisms from 3-D Surface Flaw with Varied Dipping Angle under Uniaxial Compression", Key Engineering Materials, Vols. 353-358, pp. 2353-2356, 2007
Online since
September 2007
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Price
$32.00
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